A strong earthquake killed at least 65 people in New Zealand's second-biggest city of Christchurch on Tuesday, with more casualties expected as rescuers worked into the night to find scores of people trapped inside collapsed buildings.

Israel's Foreign Ministry fears that an Israeli man may be among those killed in the quake, Israel radio reported on Tuesday. There are an estimated 120 Israelis living or traveling in Christchurch. The foreign ministry and government are currently discussing sending an aid envoy to Christchurch to help with rescue efforts.

A woman is pulled from the rubble after an earthquake in Christchurch February 22, 2011.Reuters

It was the second quake to hit the city of almost 400,000 people in five months, and New Zealand's most deadly natural disaster for 80 years.

"We may well be witnessing New Zealand's darkest day...The death toll I have at the moment is 65 and that may rise," New Zealand Prime Minister John Key told local TV.

"It's hard to describe. What was a vibrant city a few hours ago has been brought to its knees," added Key, who had flown to his home town of Christchurch, where he still has family.

The 6.3 magnitude quake struck at lunchtime, when streets and shops thronged with people and offices were still occupied.

Christchurch's mayor described the city, a historic tourist town popular with overseas students, as a war zone.

"There will be deaths, there will be a lot of injuries, there will be a lot of heartbreak in this city," Mayor Bob Parker told Australian TV by phone.

He told local radio that up to 200 could be trapped in buildings but later revised down to around 100 or so.

A man holds a child in his arms after an earthquake in Christchurch February 22, 2011.Reuters

The quake is country's worst natural disaster since a 1931 quake in the North Island city of Napier which killed 256.

All army medical staff have been mobilized, while several hundred troops were helping with the rescue, officials said.

A woman trapped in one of the buildings said she was terrified and waiting for rescuers to reach her six hours after the quake, which was followed by at least 20 aftershocks.

"I thought the best place was under the desk but the ceiling collapsed on top, I can't move and I'm just terrified," office worker Anne Voss told TV3 news by mobile phone.

Christchurch has been described as a little piece of England. It has an iconic cathedral, now largely destroyed, and a river called the Avon. It had many historic stone buildings, and is popular with English-language students and also with tourists as a springboard for tours of the scenic South Island.

Twelve Japanese students at a school in Christchurch were still missing after a building collapse, an official told Reuters in Japan. Nine Japanese students and two teachers from the same group had already been rescued or accounted for.

Emergency shelters had also been set up in local schools and at a race course, as night approached. Helicopters dumped water to try to douse a fire in one tall office building. A crane helped rescue workers trapped in another office block.

Emergency crews picked through rubble under bright lights as night fell, including a multi-story office building whose floors appeared to have pancaked on top of each other.

Christchurch is built on silt, sand and gravel, with a water table beneath. In an earthquake, the water rises, mixing with the sand and turning the ground into a swamp and swallowing up sections of road and entire cars.

TV footage showed sections of road that had collapsed into a milky, sand-colored lake right beneath the surface. One witness described the footpaths as like "walking on sand."

Unlike last year's even stronger tremor, which struck early in the morning when streets were virtually empty, people were walking or driving along streets when the shallow tremor struck, sending awnings and the entire faces of buildings crashing down.

Police said debris had rained down on two buses, crushing them, but there was no word on any casualties.

The quake hit at 12:51 pm (2351 GMT Monday) at a depth of only 4 km (2.5 miles), according to the U.S. Geological Survey.

The tremor was centered about 10 km (six miles) southwest of Christchurch, which had suffered widespread damage during last September's 7.1 magnitude quake but no deaths.

New Zealand sits between the Pacific and Indo-Australian tectonic plates and records on average more than 14,000 earthquakes a year, of which about 20 would normally top magnitude 5.0.

A building damaged by an earthquake is seen in Christchurch, New Zealand, February 22, 2011Reuters

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